Hydraulic vacuum power unit



Nov. 30, 1954 Filed June 18, 1949 E. R. PRICE HYDRAULIC VACUUM POWER UNIT 2 Sheets-Sheet l INI ENTOR.

MEA/8L E P//CE A TTOE/VEY NOV. 30, 1954 El R PRlCE 2,695,500

HYDRAULIC VACUUM POWER UNIT Filed June 18, 1949 2 Sheets-SheetZ INVENTOR..

A T TOE/VE Y 2,695,500 Patented Nov. 30, 1954 HYDRAULIC 'VACUUM `POWER i UNIT Earl R. Price, South Bendylnd., assignorto Bendix Aviation `Corporatiomsouth Bend, Ind., a corporation of :Delaware Application June 18,1949, Serial No. 100,067

9Clms. '(Cl. 60-54.6)

The present invention Vrelatesto an improvement in .hydraulic-vacuumtpower unitsof the :types Vdisclosed in .-Price .'Patent :No. 2,353,755, Ringer application Serial `:No. 1620,905, filed October 1-8, 1945, now .Patent No. .2;598;6}4, Price .applications 'Serial No :581,117, led 'Marchsi l945,.noW-'Patent.`No. 2,536,461, and Serial frNo. 751,283, lfiled 'May 29, 1947, now Patent No. 12,165 4,39 l..

Theprimary object of the.` present inventionisto provvide `a unit Similar to the `types disclosed inxthe above :dentifedzpatents and applications in which `the bending lftendencyxon. the push 4rotl connected to the powerpiston @isfreducedtoxa minimum` or completely eliminated.

4iltihasrbeen found Iin .practice that when the push rod -isrsecurely fastened to the 4power piston, a cocking or .tiltingfof'said jpower piston during the Vpower or return #strokecan` impose upon the push rod a bending torque jwhich,zunder-certain conditions, will actually bend the trod `andfcause `inoperativenessof the .unit as a whole. rlhis bending tendencyfis obviated in the `present inven- :tion byl `guiding or ysupporting the power piston `to prevent ritfrom cooking ortilting during apower stroke.

Another objectofthe present invention is to provide affluid"servomotorconstructon whereby the push rod lwillhautomatically centertitself to'compensate for manufacturing 'tolerances and anya slight' transverse shifting of either the powerA piston orv theA push rod. n

"Furtherfobjectsvand advantages willibecome apparent as thel description proceeds.

"Figure 1 illustrates a` partial axial section ofan embodimenty off the presentinvention; and Figure 2 is .a similar view of another `embodiment thereof.

ReferringV more `.particularly to Figure l ofthe draw- 4i1:tgs,la .cylindrical casing 10 houses .a `fluid pressure mesponsive'member ordisc-shaped power piston.12 which fdefinesfaftluidtight chamber on each sdethereOf, such zcbambers :being designated a'by reference numerals 14 z-and `1v6,.'respective1y. `By introducing `a pressurel diier- -ential over piston 12xwhereby thevuid pressure: in` chamsber 1.4.1exceeds the .pressure in `chamber 16, piston 12 -will-be urged towards'the right, this beingthe normal :direction for 'actuation:movement'of'the unit. Mechalnisrnsl suitable for `controlling =the :pressure Adifferential .overpiston 12.are\'wellrkno`wn\tothe -art andare there- :tfore'notillustratedrnor described. A frt1sto.-conical.com 'rpression spring18 vbiases piston `12 to itsoif or' illustrated Iposition.

:Inforderato hold piston l12-against tilting or cocking, aiguiding or supporting assembly generally indicatedby .reference 4numeral '20 is provided, ,In the illustrated `-.version,1assernbly k20consists of. an elongated cylindrical flousing22 coaxially secured at one-ofitsvends byany rsitablefmeans, i such `as the threaded :portion 24, .toithe Wall 26 of casing 10. 'Telescopically mounted `in i'housingZ'Zis a'rguideor piston `support member inthe h fotrntof a solidbarfor atube 28 whichis coaxially zfsecured. at one ,of'its` ends to;piston 12. `Tube28.is.illus tratedasbeing `suitably securedto piston 12 by means foftthe .centrallylocated .piston hub 30 which is threadedlyireceivedin .the `central portion of :piston 1-2. This pistons supportmember28 .could obviouslybe formed integral eitherfthecentraleportion ,ofpiston `12 or ttheffhubf30. l'Ihus .the "piston 12 is Vlactually.constituted thedisc: portion-:oa .the 4pis'tonf itself and the 'elongated -Szguidezorasupport'member 28. Anytendencyzfor piston tocock is: preventedf by .this-r tube w28.

vlength of Athe Vpush rod 34 Hub 30 is provided with a recessed portion 321for receiving the rounded endof;thrusttransmitting member or push rod .34 whose `axis is collinear `with thatof `the guide or support assembly 20. The rear wall .36 `of recess 32 is preferably formed with aslight concavity or curvature having a radius substantially equal to the rod 34, Vthis v.curvature being exaggerated :in the illustrations `for purposes of clarity, for a reason to be explained `hereafter. To .hold the .convex end 33 of push rod 34 againstconcave wall 36, a `frusto- `conical shaped spring V39 surrounds such :end `to bear against a collar 3S. and ,washer 37 on rod 34 and a retainer ring 40 nestedin aperipheral groove 41 in thewall'of the recess,32. Since retainer40 is secured =in.groove v41 in recess 32 of vhub 30, and spring 39.is :compressed between collar 38 and washer 3-'7 adjacent `thereto .on rod '34, the convex end of rod34 is vurgedinto contact `withthe concave wall 36 ofrecess 32. Furthermore, `inasmuch as the rod is of a diameter fsmaller `than recess .532, lateral sliding contactis .permitted between the .rod end and recess limited only by thewidth-of said recess. The other end of push `rod 34 is connected ftothehydraulic piston assembly generally indicated by reference numeral 42.

In operation, ascxplained previously, a pressure differential overpiston 12 whereinthepressure `in chamber v14 exceeds that in .chamber 1.6, piston 12'willbetmoved towards the right'thereby :pushing rrod `34 :against Whatever reaction mightbe present on the piston .assembly 42. The curvature of the wall in recess 32 permits the vmating end`.33 `of rod.34tomove alongrthewall surface until the rod becomes centered. It is readily apparent .that the support member 28 which .istshownlas screwed into-hub 30, is in'ieifect piston12, through housing22, in a xed recip- `rocable relationship with respect to `housing -10 of the power unit. 'I'hus if the casing -10 and the piston 12 or any of the other:parts are out of concentricity, the will find its own center .xthroughthe previously mentioned iiexible sliding connection Withrespect tohub 30 which `is a part ofpiston 12 and willftake, under operation, .only inonbendingt` compressive forces.

'In Figure l2 is illustrated another embodiment of the present invention', like parts -carryingzthe Asame reference numeralswith primemarksyin whichxthe guide construction -20 isjdsposed oppositely toithat offFigure l. -In this embodiment, a :support tube.28 is coaxially `secured to-piston-IZ' on one endgand is Similarlyrsecured to a guide disc 44,*which lies in afplanecparallel to piston 12', onits'other end. Suitably coaxiallyxsecured to the interior of tube 28 isa sockettmember 330 `constructed similarly to that .ofghub 30`in;Figure 1. Here, as in Figurel, the tube 28 maybe formed integrally'with the central portionfof-` piston-12 or hub 60.

AnyA tendency ofipiston 12'- tofcockr or tilt isprevented by'the engagement of disc `44^with the wall-of casing 10,..and Vany ,eccentricity` of the powerA cylinder parts will becompen'satedfor bythe vslidingmovernent of the push rod 34 onithecurvedend wall'. of .socketlmember 30.

Although only two embodimentsfof the invention have been illustrated tand described,?various changes in the `form and `relative arrangements of lthe Vparts may be :pistonhavin'g a hub centrally .secured-thereto, an elon- 'gated:tubular-member coaxially secured to `said hub,

afstationary supporting cylinder telescopieally receiving andbeing axially coeXtensive `with said tubular member whenisaid piston is in retracted position,` the. end'of said tubular'member being continuously inside said vvsupport- `ing cylinder .for theentire protrae/tile `stroke of.said piston, said hub -being"formedrzwith:an axial recess on its side opposite. said tubular member, the end wall of said -recess being. formed with a'concave surface, a push rod collinearly .disposed with Arespect to said Vtubular `member having .gone -end in .Contact -vwith said concave surface, said end'ofxsaid-rod-being `formed with-acmed end surface, a spring :retainer .on vsalidtrod inearsaid curved-end within said recess, a second sprlng `retainer on the interior` of Lsaitl recess near Vthe mouth-thereof.

and a frusto-conical compression spring surrounding said push rod and compressed between said spring retainers to urge the curved end of said rod against said concave surface and to coaxially center said rod with respect to said piston.

2. In a huid-operated power cylinder, a reciprocable disc-shaped piston having a hub secured thereto, an elongated tubular member coaxially secured to said hub, a stationary supporting cylinder telescopically fitted over said tubular member, the end of said tubular member opposite said piston fitting within said supporting cylinder for the entire reciprocal stroke of said piston, said hub being formed with an axial recess on its side oppo site said tubular member, the end wall of said recess being formed with a spherical surface, a push rod collinearly disposed with respect to said tubular member having one end in contact with said spherical surface, a spring retainer on said rod near said end within said recess, a second spring retainer on the interior of said recess near the mouth thereof, and a frusto-conical compression spring surrounding said push rod and compressed between said spring retainers to urge said end of said rod against said spherical surface and to center said rod with respect to said piston.

3. In a fluid-operated power cylinder, a Huid pressure responsive member, a support member coaxially secured to said pressure responsive member, a stationary guide member cooperatively associated with said support member to allow only axial movement thereof, a recess including a curved surface centrally located on said pressure responsive member on the side opposite said support member, a thrust transmitting member having its axis substantially coincident with that of said pressure responsive member and having one end curved and in lateral sliding engagement with said curved surface of said recess, said thrust transmitting member being proportioned with respect to said recess so that the thrust member in said recess has substantial lateral movement therein to compensate for axial misalignment of the reciprocable parts in said fluid-operated power cylinder, and a compression spring surrounding said pressure transmitting member to urge it into engagement with said curved surface and into line with the axis of said uid responsive member.

4. In a huid-operated power cylinder, a fluid pressure responsive member, a support member coaxially secured to said uid responsive member, a stationary guide member cooperatively associated with said support member to allow only axial movement thereof, a concave surface centrally located in a recess on said fiuid responsive member on the side opposite said support member, a thrust transmitting member having its axis substantially coincident with that of said uid responsive member and having one convex end in lateral sliding engagement with said concave surface of said recess, said thrust transmitting member being of a substantially smaller width than that of said recess, said thrust member being operable to move laterally within said recess to compensate for axial misalignment of the parts of the Huid-operated power cylinder, and means engaged between said pressure responsive member and thrust member yieldably urging said thrust transmitting member into its aforementioned axial position and into engagement with said concave surface.

5. In'a Huid-operated power cylinder, a fiuid pressure responsive member, a support member coaxially secured to said fluid responsive member, a stationary guide member cooperatively associated with said support member to allow only axial movement thereof, a thrust surface centrally located in a recess on said fluid responsive member on the side opposite said support member, a p ressure transmittingmember having its axis substantlally coincident with that of said uid responsive member and having one end in lateral sliding engagement with said thrust surface, of said recess, said thrust transmitting member being proportioned with respect to said recess and operable to move laterally therein, permitting compensation for axial misalignment of the fluid pressure responsive member and the pressure transmitting member, and means engaged between the liuid pressure responsive member and the thrust transmitting member yieldably urgingsaid pressure transmitting member into 1ts aforementioned axial position.

.6. In a fluid-operated power cylinder, a disc-shaped piston responsive to differential uid pressure, a tubular member coaxially secured to said piston at one end and movable with the piston to allow only axial movement thereof, a disc-shaped guide member lying in a plane parallel to the plane of said piston and coaxially secured to the other end of said tubular member, the periphery of said guide member slidably engaging the interior of the power cylinder, a concave wall formed in the end of said tubular member adjacent said piston, a push rod extending into said tubular member and having its axis substantially coincident with the axis of said tubular member, one end of said rod being convex to conform with the concave wall and being in lateral sliding engagement with said wall, said rod being proportioned with respect to said concave wall permitting substantial lateral movement in said tubular member and resilient means between said tubular members and said rod urging said one end of said rod into engagement with said wall and said rod into the aforementioned axial coincidence.

7. In a huid-operated power cylinder, a substantially flat disk-shaped piston adapted to reciprocate in the power cylinder, a hub rigidly supported in the central portion of said piston and having a cylindrical recess formed on an axis substantially coincident with the axis of said piston, an elongated tubular member coaxially and rigidly secured with respect to the cylindrical recess of said hub, a guide means surrounding the end of said tubular member opposite the piston throughout the entire piston stroke to allow substantially only translatory axial movement of said tubular member and said piston, a concave surface formed in the end wall of the hub recess, the center of curvature of which lies substantially on the axis of said piston, a push rod collinearly disposed with respect to the axis of said piston and having one end in sliding contact with said concave surface, said end of said rod being rounded and having a radius which will permit sliding contact with said concave surface, a spring retainer on said rod near said rounded end and within said recess, a second spring retainer carried in the hub recess near the mouth thereof, and a compression spring surrounding said push rod and being compressed between said spring retainers to urge the corresponding end of said rod into contact with said concave surface and to maintain said rod substantially axially centered, with respect to said piston, on said concave surface, the aforementioned sliding contact permitting slight shifting movement of said push rod with respect to said piston during movement of the latter to reduce the bending tendency imposed on said rod caused by slight eccentricities between the piston and rod.

8. In a duid-operated power cylinder, a substantially fiat disk-shaped piston adapted to reciprocate in the power cylinder, a hub rigidly supported in the central portion of said piston and having a recess formed therein, an elongated tubular member coaxially and rigidly secured with respect to the recess of said hub, a guide means telescopically associated with said tubular member to allow substantially only translatory axial movement of said tubular member and said piston, said guide means surrounding the end of said tubular member opposite said piston throughout the entire piston stroke, a concave surface formed in the end wall of the hub recess, theV center of curvature of which lies substantially on the axis of said piston, a push rod collinearly disposed with respect to the axis of said piston and having one end'in sliding contact with said concave surface, said end of said rod being rounded and having a radius which will permitsliding contact with said concave surface, a spring retainer on said rod near said rounded end,.a second spring retainer carried in the hub recess near the mouth thereof, and a compression spring surrounding said push rod and being compressed between said spring retainers to urge the corresponding end of said rod into contact with said concave surface and to maintain said rod substantially axially centered, with respect to said piston, on said concave surface, the aforementioned sliding contact permitting slight shifting movement of said push rod with respect to said piston during movement of the latter to reduce the bending 'tendency imposed on said rod caused by slight eccentricities between the piston and rod.

9. In a huid-operated power cylinder, a piston adapted to reciprocate in the power cylinder and having a concave surface formed in a recess in the central portion thereof with the center of curvature lying substantially on the axis of said piston, a push rod operatively connected to said piston and having an axis extending substantially coincident with that of said piston, one end yof said rod being convex and being in lateral sliding engagement with said concave surface, said rod having a diameter which is substantially snr-:aller than the recess which will permit the aforementioned sliding engagement, a spring retainer on said rod near said convex end, a second spring retainer rigidly supported with respect to said piston and being axially spaced from said first retainer, and a compression spring surrounding said push rod and being compressed between said spring retainers to urge the corresponding end of said rod into contact with said concave surface and to maintain said rod substantially axially centered with respect to said piston on said concave surface, the aforementioned sliding contact permitting lateral shifting movement of said push rod with respect to said piston during movement of the latter to reduce the bending tendency imposed on said rod caused by slight eccentricities between the piston and rod, and a support member coaXially secured to said piston and a stationary guide member cooperatively associated with said support member to allow only axial movement of said piston, whereby the lateral shifting movement of said rod cornpensates for axial misalignment of said piston and rod upon actuation of the power piston.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 761,339 Thomas May 31, 1904 1,042,849 Vanderleast Oct. 29, 1912 1,491,797 Harrison Apr. 29, 1924 2,298,314 Sauzedde Oct. 13, 1942 2,336,374 Stelzer Dec. 7, 1943 2,444,181 Baldwin June 29, 1948 2,463,537 Hoar et al. Mar. 8, 1949 2,467,517 Almond Apr. 19, 1949 2,477,882 La Brie Aug. 2, 1949 FOREIGN PATENTS Number Country Date 273,237 Great Britain Mar. 5, 1928 365,717 Great Britain Ian. 28, 1932 

